Effect of the V/III ratio during buffer layer growth on the yellow and blue luminescence in undoped GaN epilayer

Effect of the V/III ratio during buffer layer growth on the yellow and blue luminescence in undoped GaN epilayer has been studied by means of photoluminescence spectroscopy and high resolution X-ray diffraction. It is found that the densities of screw and edge threading dislocations increase with the V/III ratio of the buffer layer, and the intensities of the yellow luminescence (YL) and blue luminescence (BL) emissions also increase dramatically. However, the density ratio of the edge threading dislocation to the screw threading dislocation remains invariant, as well as the intensity ratio of YL emission to BL emission. It can be concluded from these phenomena that the edge threading dislocation and screw threading dislocation can enhance the YL and BL emissions, respectively.